Mushroom plant

ABSTRACT

A new and distinct variety of mushroom is described. This variety is similar to a type called &#34;off-white&#34; in the trade. The new variety possesses advantages of both productivity and yield when compared to two commercially available line 348 and Moonlite™. The novel variety also displays a unique electrophoretic isozyme pattern.

The present invention relates to a new and distinct variety of mushroomplant of Agaricus brunnescens Peck [=A. bisporus (Lange) Imbach].

No other major commercially important crop has experienced as littlegenetic improvement as the common edible mushroom, Agaricus brunnescensPeck. [=Agaricus bisporus (Lange) Imbach]. This situation has been dueexclusively to the unique genetic life history of this fungus whichhinders and often precludes manipulation of the germ plasm without theuse of specific codominant markers. Unlike other Agaricus spp., Agaricusbrunnescens is primarily two-spored.

Selective breeding programs for A. brunnescens have been proposed whichutilize auxotrophic mutants (Raper and Raper, Mush. Sci. 8:1-9 (1972));Raper et al., Mycologia 64:1088-1172, (1972)), mycelial fusion andnuclear exchange between heterokaryotic lines (Moessner, Mush. Sci.5:197-203 (1962)), multispore-derived cultures (Stubnya, Mush. Sci.10(1); 83-89 (1979)), or resistance to biocides (Elliott, Mush. Sci. 10(1):73-81 (1979)). Each of these approaches has the disadvantage that alimited number of crosses can be made, corroborated, and uniquelymarked.

Isozyme analysis has proved to be a potent genetic tool because of theinterpretable, one-to-one relationship of isozyme phenotype to theorganism's genotype. The single-gene basis of observed electrophoreticvariation in fungi by the use of single-spore-derived isolates has beenshown for Conidiobolus thromboides Dreschler [syn, Entomophthoravirulenta Hall et Dunn] (May et al. Exp. Mycol 3:289-297 (1979)),Agaricus campestris (May and Royse Mush. Sci. 11(2):799-817 (1981); andBiochem. Genet. 20:1165-1173, (1982)), and A. brunnescens (May and Roysesupra (1981); and Royse and May Mycologia 74:93-102 (1982). For A.brunnescens isozyme analysis allows the ability to distinguishhomokaryotic from heterokaryotic single-spore-derived lines.

On the basis of five variable biochemical loci Royse and May, (supra,1982) were able to partition lines of A. brunnescens into genotypicclasses. Combining the number of genotypes possible at each locus wouldallow over 20,000 recognizable genotypic classes. The finding of onlyfive genotypic classes among 34 commercial lines and only 27 classes in162 lines in The Pennsylvania State University Mushroom CultureCollection is further evidence that little of the potential genotypicvariability is expressed in the stocks examined.

The novel variety described herein was produced as a result of thebreeding program in the Department of Plant Pathology, The PennsylvaniaState University. The invention was completed in two major phases: (1)crossing of two compatible breeding stocks (homokaryons) and (2)evaluation of desirable cultivation characteristics of the new hybrid.The new line was produced by crossing homokaryons derived from a goldenwhite parent (232) commonly used in cave culture and a light creamparent (266) not commonly used for commercial cultivation. The improvedcharacteristic of this mushroom line is its increased yield in Kg/m² ascompared to the yield and size of the golden white variety (232).

The A. brunnescens isolates (232 and 266) were from The PennsylvaniaState University Mushroom Culture Collection (PSUMCC). These lines havebeen electrophoretically typed by Royse and May (supra, 1982) and Mayand Royse (supra, 1982). Allelic variability represented in the PSUMCCis diagramatically represented in FIG. 1. The alleles for lines 232 and266 at six biochemical loci are listed in Table 1.

Homokaryons were derived from lines 232 and 266 and used as breedingstock. The general scheme followed that presented in FIG. 2. The allelesfor these homokaryons (232-58 and 266-324) are listed in Table 2. Thecultures 232-58 and 266-324 were set up in dual culture as outlined byMay and Royse (supra 1982). The alleles possessed by the resultinghybrid are listed in Table 3. The hybrid's allelic combination is uniqueto any commercial or PSUMCC isolates and can be easily distinguishedfrom any of these isolates.

Evaluation of the hybrid's characteristics for commercial desirabilitywere performed at the Mushroom Research Center of The Pennsylvania StateUniversity, University Park Pa. The hybrid was subjected to two (2) cropevaluations on two (2) different composts using commercial lines forcomparisons. A summary of the results are presented in Tables 4 and 5.As can be seen from these tables, BB32 (F₁ hybrid) is generally superiorin yield to the checks or commercial lines examined (Table 4). In bothevaluations (Table 4) the novel line was significantly better than theMoonlite™ line. Yield for BB32 was also significantly higher than thecommercial line (348) in crop 82-24 (Table 4). There was no significantdifference in yield between 348 and BB32 for crop 82-18.

Mushroom size (Table 5) was significantly greater for BB32 than for thecommercial line 348 for both crops. BB32 also was significantly largerthan the commercial Moonlite™ line for crop 82-14, but there was nosignificant difference in size between these two lines for crops 82-18.In summary, the newly developed line has advantages in both size andyield when compared to two commercially used lines (348 and Moonlite™).

Mushroom hybrid BB32 is of a type similar to one called "off-white" inthe trade such as Darlington 11 or Darlington 76. The cap is scaly and"off-white" in color. Normally, this mushroom is colored an off-whiteand is moderately scaled; however, under drought conditions orrelatively high air movement the caps are quite scaly and coloredcreamish-white. At maturity the cap frequently is domed. The caps andstalks of this mushroom are thicker than the typical "white" and"off-white" mushrooms.

The cap or pileus of the mushroom, when the veil breaks, varies between25-150 mm in diameter and is of generally convex shape.

The stipe is 25-80 mm long, 8-25 mm thick, strongly bulbous in thebutton stage but becoming cylindrical at maturity.

The lamellae are whitish at first but become a pinkish flesh color bythe time the veil breaks. Later the gills become a purplish brown andfinally a chocolate brown as the spores mature. The gills are free,crowded, conspicuously white-marginate, with lamellae interspersed.

The annulus is prominent and fairly persistent, composed of a singletype, formed from a velar sheath over the stipe extending up to themargin of the unexpanded pileus.

The flesh is white, turning bright pinkish red in approximately 2 min.when cut or bruised (particularly int the stipe) and later turningbrown. The flesh is quite thick below the disc.

The pileus cuticle is composed of radially arranged, repent, parallel tointerwoven, clampless, hyaline to creamish hyphae measuring 2.5-12 μmdiameter. The pileus trama is composed of large, thin-walled,interwoven, clampless hyphae measuring 4-32 μm diameter. Pleurocystidiaare lacking. Cheilocystidia are abundant and form a continuous steriletissue, clavate to cylindrical or fusoid, often rather irregular inshape, not clamped at the base, and measuring 14-35×5.5-14 μm. Thebasidia are mostly 2-spored (rarely 1, 3, or 4-spored), clavate, notclamped at the base, and measure 18-36×6-8 μm. The basidiospores arebroadly elliptical to slightly ovate in face view, unilaterallyflattened- elliptical to -ovate in side view, smooth, thick-orthin-walled, lacking a germ pore, dark brown in mass, and measure6.1-9.2×4.6-7.0 μm.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates the allelic variability of Agaricus brunnescenscultures from The Pennsylvania State University Mushroom CultureCollection and from commercial spawn makers.

FIG. 2 illustrates a strategy for confirmation of hybridization andsubsequent hybrid evaluation in the common cultivated mushroom.

a. Selection from germ plasm bank of parental breeding stock withalternate electrophoretic types.

b. Dual culture of parental lines on agar plates.

c. Selection of possible hybrid mycelium from interaction zone.

d. Culture of selection in liquid medium.

e. Electrophoretic confirmation of hybrid; types 1 and 2=parental lines;type 3=hybrid (note "extra" band); type 4=mix only of parental lines.

f. Production of spawn from confirmed hybrids for spawning compost.

g. Selection among different hybrid lines for desirable traits.

FIG. 3 is a photograph showing two forms of the mushroom plants of thepresent invention.

                  TABLE 1                                                         ______________________________________                                        Alleles possessed by the parental lines used to                               derive homokaryotic breeding stock for hybrid                                 production                                                                    BIOCHEMICAL LOCI                                                              Line                 Pep-    Pep-                                             No.  Gpt      Mpi    LLL-1   LLL-2  Adh    Aat                                ______________________________________                                        232  100/165  .0..sup.a                                                                            100/115 100/100                                                                              100/149                                                                              81/100                             266  100/139  .0..sup.                                                                             100/115 100/111                                                                              100/165                                                                              81/100                             ______________________________________                                         .sup.a No activity                                                       

                  TABLE 2                                                         ______________________________________                                        Alleles possessed by homokaryotic breeding                                    stock for hybrid production                                                   BIOCHEMICAL LOCI                                                              Line No.                                                                             Gpt     Mpi    Pep-LLL-1                                                                             Pep-LLL-2                                                                             Adh   Aat                               ______________________________________                                        232-58 165     .0..sup.a                                                                            115     100     100    81                               266-324                                                                              139     .0..sup.                                                                             100     111     100   100                               ______________________________________                                         .sup.a No activity                                                       

                  TABLE 3                                                         ______________________________________                                        Alleles possessed by novel hybrid as a result                                 of crossing homokaryotic breeding stock                                       BIOCHEMICAL LOCI                                                              Line                  Pep-   Pep-                                             No.   Gpt      Mpi    LLL-1  LLL-2  Adh    Aat                                ______________________________________                                        BB32  139/165  .0..sup.a                                                                            100/115                                                                              100/111                                                                              100/100                                                                              81/100                             (Hy-                                                                          brid)                                                                         ______________________________________                                         .sup.a No activity                                                       

                  TABLE 4                                                         ______________________________________                                        Mushroom yield in lbs/ft.sup.2 for crops 82-18 and                            82-24 grown at The Mushroom Research Center of The                            Pennsylvania State University.                                                                 Crop #                                                       Line #             82-18    82-24                                             ______________________________________                                        266 (parent 1)     1.86   a*      1.81 a*                                     BB32 (F.sub.1 hybrid)                                                                            1.54   b       1.57 b                                      348 (check)        1.53   b       1.32 c                                      BB32/1169 (F.sub.2 hybrid)                                                                       1.51   b       1.52 bc                                     Moonlite ™  (check)                                                                           1.22   c       1.22 d                                      232 (parent 2)     1.02   d       1.31 cd                                     ______________________________________                                         *Means followed by the same letter within the same column are not             significantly different based on the WallerDuncan KRatio TTest at P =         0.05.                                                                    

                  TABLE 5                                                         ______________________________________                                        Mushroom size in grams/mushroom for crops 82-18                               and 82-14 grown at The Mushroom Research Center of The                        Pennsylvania State University.                                                                 Crop #                                                       Line #             82-18    82-24                                             ______________________________________                                        BB32 (F.sub.1 hybrid)                                                                            7.30   a*      6.68 a*                                     232 (parent 2)     7.29   a       5.38 b                                      Moonlite ™ (check)                                                                            6.82   ab      5.10 bc                                     348 (check)        6.67   b       4.64 c                                      BB32/1169 (F.sub.2 hybrid)                                                                       6.41   b       6.20 b                                      266 (parent 1)     5.35   c       5.14 bc                                     ______________________________________                                         *Means followed by the same letter within the same column are not             significantly different based on the WallerDuncan KRatio TTest at P =         0.05.                                                                    

What is claimed is:
 1. A new and distinct variety of mushroom plantsubstantially as shown and described characterized particularly as tonovelty by its greater productivity and yield when compared to twocommercially available lines, 348 and Moonlite™ and by its uniqueelectrophoretic isozyme phenotype.